licence.c

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/* -*- c-basic-offset: 8 -*-
   rdesktop: A Remote Desktop Protocol client.
   RDP licensing negotiation
   Copyright (C) Matthew Chapman <matthewc.unsw.edu.au> 1999-2008
   Copyright (C) Thomas Uhle <thomas.uhle@mailbox.tu-dresden.de> 2011
   Copyright (C) Henrik Andersson <henrik.andersson@cendio.com> 2014
 
 
   This program is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.
 
   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.
 
   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/
 
#include "precomp.h"
 
void *
rdssl_rc4_info_create(void);
void
rdssl_rc4_info_delete(void * rc4_info);
void
rdssl_rc4_set_key(void * rc4_info, char * key, int len);
void
rdssl_rc4_crypt(void * rc4_info, char * in_data, char * out_data, int len);
int
rdssl_mod_exp(char* out, int out_len, char* in, int in_len,
              char* mod, int mod_len, char* exp, int exp_len);
 
extern char g_username[256];
extern char g_hostname[256];
extern RDP_VERSION g_rdp_version;
 
static uint8 g_licence_key[16];
static uint8 g_licence_sign_key[16];
 
RD_BOOL g_licence_issued = False;
RD_BOOL g_licence_error_result = False;
 
/* Generate a session key and RC4 keys, given client and server randoms */
static void
licence_generate_keys(uint8 * client_random, uint8 * server_random, uint8 * pre_master_secret)
{
    uint8 master_secret[48];
    uint8 key_block[48];
 
    /* Generate master secret and then key material */
    sec_hash_48(master_secret, pre_master_secret, client_random, server_random, 'A');
    sec_hash_48(key_block, master_secret, server_random, client_random, 'A');
 
    /* Store first 16 bytes of session key as MAC secret */
    memcpy(g_licence_sign_key, key_block, 16);
 
    /* Generate RC4 key from next 16 bytes */
    sec_hash_16(g_licence_key, &key_block[16], client_random, server_random);
}
 
static void
licence_generate_hwid(uint8 * hwid)
{
    buf_out_uint32(hwid, 2);
    strncpy((char *) (hwid + 4), g_hostname, LICENCE_HWID_SIZE - 4);
}
 
/* Send a lincece info packet to server */
static void
licence_info(uint8 * client_random, uint8 * rsa_data,
         uint8 * licence_data, int licence_size, uint8 * hwid, uint8 * signature)
{
    uint32 sec_flags = SEC_LICENSE_PKT;
    uint16 length =
        24 + SEC_RANDOM_SIZE + SEC_MODULUS_SIZE + SEC_PADDING_SIZE +
        licence_size + LICENCE_HWID_SIZE + LICENCE_SIGNATURE_SIZE;
    STREAM s;
 
    s = sec_init(sec_flags, length + 2);
 
    out_uint8(s, LICENCE_TAG_LICENCE_INFO);
    out_uint8(s, ((g_rdp_version >= RDP_V5) ? 3 : 2));  /* version */
    out_uint16_le(s, length);
 
    out_uint32_le(s, 1);
    out_uint16(s, 0);
    out_uint16_le(s, 0x0201);
 
    out_uint8p(s, client_random, SEC_RANDOM_SIZE);
    out_uint16_le(s, 2);
    out_uint16_le(s, (SEC_MODULUS_SIZE + SEC_PADDING_SIZE));
    out_uint8p(s, rsa_data, SEC_MODULUS_SIZE);
    out_uint8s(s, SEC_PADDING_SIZE);
 
    out_uint16_le(s, 1);
    out_uint16_le(s, licence_size);
    out_uint8p(s, licence_data, licence_size);
 
    out_uint16_le(s, 1);
    out_uint16_le(s, LICENCE_HWID_SIZE);
    out_uint8p(s, hwid, LICENCE_HWID_SIZE);
 
    out_uint8p(s, signature, LICENCE_SIGNATURE_SIZE);
 
    s_mark_end(s);
    sec_send(s, sec_flags);
}
 
/* Send a new licence request packet */
static void
licence_send_new_licence_request(uint8 * client_random, uint8 * rsa_data, char *user, char *host)
{
    uint32 sec_flags = SEC_LICENSE_PKT;
    uint16 userlen = strlen(user) + 1;
    uint16 hostlen = strlen(host) + 1;
    uint16 length =
        24 + SEC_RANDOM_SIZE + SEC_MODULUS_SIZE + SEC_PADDING_SIZE + userlen + hostlen;
    STREAM s;
 
    s = sec_init(sec_flags, length + 2);
 
    out_uint8(s, LICENCE_TAG_NEW_LICENCE_REQUEST);
    out_uint8(s, ((g_rdp_version >= RDP_V5) ? 3 : 2));  /* version */
    out_uint16_le(s, length);
 
    out_uint32_le(s, 1);    // KEY_EXCHANGE_ALG_RSA
    out_uint16(s, 0);
    out_uint16_le(s, 0xff01);
 
    out_uint8p(s, client_random, SEC_RANDOM_SIZE);
    out_uint16_le(s, 2);
    out_uint16_le(s, (SEC_MODULUS_SIZE + SEC_PADDING_SIZE));
    out_uint8p(s, rsa_data, SEC_MODULUS_SIZE);
    out_uint8s(s, SEC_PADDING_SIZE);
 
    /* Username LICENSE_BINARY_BLOB */
    out_uint16_le(s, BB_CLIENT_USER_NAME_BLOB);
    out_uint16_le(s, userlen);
    out_uint8p(s, user, userlen);
 
    /* Machinename LICENSE_BINARY_BLOB */
    out_uint16_le(s, BB_CLIENT_MACHINE_NAME_BLOB);
    out_uint16_le(s, hostlen);
    out_uint8p(s, host, hostlen);
 
    s_mark_end(s);
    sec_send(s, sec_flags);
}
 
/* Process a licence request packet */
static void
licence_process_request(STREAM s)
{
    uint8 null_data[SEC_MODULUS_SIZE];
    uint8 *server_random;
    uint8 signature[LICENCE_SIGNATURE_SIZE];
    uint8 hwid[LICENCE_HWID_SIZE];
    uint8 *licence_data;
    int licence_size;
    void * crypt_key;
 
    /* Retrieve the server random from the incoming packet */
    in_uint8p(s, server_random, SEC_RANDOM_SIZE);
 
    /* We currently use null client keys. This is a bit naughty but, hey,
       the security of licence negotiation isn't exactly paramount. */
    memset(null_data, 0, sizeof(null_data));
    licence_generate_keys(null_data, server_random, null_data);
 
    licence_size = load_licence(&licence_data);
    if (licence_size > 0)
    {
        /* Generate a signature for the HWID buffer */
        licence_generate_hwid(hwid);
        sec_sign(signature, 16, g_licence_sign_key, 16, hwid, sizeof(hwid));
 
        /* Now encrypt the HWID */
        crypt_key = rdssl_rc4_info_create();
        rdssl_rc4_set_key(crypt_key, (char *)g_licence_key, 16);
        rdssl_rc4_crypt(crypt_key, (char *)hwid, (char *)hwid, sizeof(hwid));
        rdssl_rc4_info_delete(crypt_key);
 
#if WITH_DEBUG
        DEBUG(("Sending licensing PDU (message type 0x%02x)\n", LICENCE_TAG_LICENCE_INFO));
#endif
        licence_info(null_data, null_data, licence_data, licence_size, hwid, signature);
 
        xfree(licence_data);
        return;
    }
 
#if WITH_DEBUG
    DEBUG(("Sending licensing PDU (message type 0x%02x)\n", LICENCE_TAG_NEW_LICENCE_REQUEST));
#endif
    licence_send_new_licence_request(null_data, null_data, g_username, g_hostname);
}
 
/* Send a platform challenge response packet */
static void
licence_send_platform_challenge_response(uint8 * token, uint8 * crypt_hwid, uint8 * signature)
{
    uint32 sec_flags = SEC_LICENSE_PKT;
    uint16 length = 58;
    STREAM s;
 
    s = sec_init(sec_flags, length + 2);
 
    out_uint8(s, LICENCE_TAG_PLATFORM_CHALLANGE_RESPONSE);
    out_uint8(s, ((g_rdp_version >= RDP_V5) ? 3 : 2));  /* version */
    out_uint16_le(s, length);
 
    out_uint16_le(s, 1);
    out_uint16_le(s, LICENCE_TOKEN_SIZE);
    out_uint8p(s, token, LICENCE_TOKEN_SIZE);
 
    out_uint16_le(s, 1);
    out_uint16_le(s, LICENCE_HWID_SIZE);
    out_uint8p(s, crypt_hwid, LICENCE_HWID_SIZE);
 
    out_uint8p(s, signature, LICENCE_SIGNATURE_SIZE);
 
    s_mark_end(s);
    sec_send(s, sec_flags);
}
 
/* Parse a platform challenge request packet */
static RD_BOOL
licence_parse_platform_challenge(STREAM s, uint8 ** token, uint8 ** signature)
{
    uint16 tokenlen;
 
    in_uint8s(s, 6);    /* unknown: f8 3d 15 00 04 f6 */
 
    in_uint16_le(s, tokenlen);
    if (tokenlen != LICENCE_TOKEN_SIZE)
    {
        error("token len %d\n", tokenlen);
        return False;
    }
 
    in_uint8p(s, *token, tokenlen);
    in_uint8p(s, *signature, LICENCE_SIGNATURE_SIZE);
 
    return s_check_end(s);
}
 
/* Process a platform challenge packet */
static void
licence_process_platform_challenge(STREAM s)
{
    uint8 *in_token = NULL, *in_sig;
    uint8 out_token[LICENCE_TOKEN_SIZE], decrypt_token[LICENCE_TOKEN_SIZE];
    uint8 hwid[LICENCE_HWID_SIZE], crypt_hwid[LICENCE_HWID_SIZE];
    uint8 sealed_buffer[LICENCE_TOKEN_SIZE + LICENCE_HWID_SIZE];
    uint8 out_sig[LICENCE_SIGNATURE_SIZE];
    void * crypt_key;
 
    /* Parse incoming packet and save the encrypted token */
    licence_parse_platform_challenge(s, &in_token, &in_sig);
    memcpy(out_token, in_token, LICENCE_TOKEN_SIZE);
 
    /* Decrypt the token. It should read TEST in Unicode. */
    crypt_key = rdssl_rc4_info_create();
    rdssl_rc4_set_key(crypt_key, (char *)g_licence_key, 16);
    rdssl_rc4_crypt(crypt_key, (char *)in_token, (char *)decrypt_token, LICENCE_TOKEN_SIZE);
    rdssl_rc4_info_delete(crypt_key);
    
    /* Generate a signature for a buffer of token and HWID */
    licence_generate_hwid(hwid);
    memcpy(sealed_buffer, decrypt_token, LICENCE_TOKEN_SIZE);
    memcpy(sealed_buffer + LICENCE_TOKEN_SIZE, hwid, LICENCE_HWID_SIZE);
    sec_sign(out_sig, 16, g_licence_sign_key, 16, sealed_buffer, sizeof(sealed_buffer));
 
    /* Now encrypt the HWID */
    crypt_key = rdssl_rc4_info_create();
    rdssl_rc4_set_key(crypt_key, (char *)g_licence_key, 16);
    rdssl_rc4_crypt(crypt_key, (char *)hwid, (char *)crypt_hwid, LICENCE_HWID_SIZE);
 
    licence_send_platform_challenge_response(out_token, crypt_hwid, out_sig);
}
 
/* Process a new licence packet */
static void
licence_process_new_license(STREAM s)
{
    void * crypt_key;
    uint32 length;
    int i;
 
    in_uint8s(s, 2);    // Skip license binary blob type
    in_uint16_le(s, length);
    if (!s_check_rem(s, length))
        return;
 
    crypt_key = rdssl_rc4_info_create();
    rdssl_rc4_set_key(crypt_key, (char *)g_licence_key, 16);
    rdssl_rc4_crypt(crypt_key, (char *)s->p, (char *)s->p, length);
    rdssl_rc4_info_delete(crypt_key);
 
    /* Parse NEW_LICENSE_INFO block */
    in_uint8s(s, 4);    // skip dwVersion
 
    /* Skip strings, Scope, CompanyName and ProductId to get
       to the LicenseInfo which we store in license blob. */
    length = 0;
    for (i = 0; i < 4; i++)
    {
        in_uint8s(s, length);
        in_uint32_le(s, length);
        if (!s_check_rem(s, length))
            return;
    }
 
    g_licence_issued = True;
    save_licence(s->p, length);
}
 
/* process a licence error alert packet */
void
licence_process_error_alert(STREAM s)
{
    uint32 error_code;
    uint32 state_transition;
    uint32 error_info;
    in_uint32(s, error_code);
    in_uint32(s, state_transition);
    in_uint32(s, error_info);
 
    /* There is a special case in the error alert handling, when licensing is all good
       and the server is not sending a license to client, a "Server License Error PDU -
       Valid Client" packet is sent which means, every thing is ok.
 
       Therefor we should flag that everything is ok with license here.
     */
    if (error_code == 0x07)
    {
        g_licence_issued = True;
        return;
    }
 
    /* handle error codes, for now, just report them */
    switch (error_code)
    {
        case 0x6:   // ERR_NO_LICENSE_SERVER
            warning("License error alert from server: No license server\n");
            break;
 
        case 0x8:   // ERR_INVALID_CLIENT
            warning("License error alert from server: Invalid client\n");
            break;
 
        case 0x4:   // ERR_INVALID_SCOPE
        case 0xb:   // ERR_INVALID_PRODUCTID
        case 0xc:   // ERR_INVALID_MESSAGE_LENGTH
        default:
            warning("License error alert from server: code %u, state transition %u\n",
                error_code, state_transition);
            break;
    }
 
    /* handle error codes, for now, just report them */
    switch (error_info)
    {
        default:
            break;
    }
 
    g_licence_error_result = True;
}
 
 
/* Process a licence packet */
void
licence_process(STREAM s)
{
    uint8 tag;
 
    in_uint8(s, tag);
    in_uint8s(s, 3);    /* version, length */
 
#if WITH_DEBUG
    DEBUG(("Received licensing PDU (message type 0x%02x)\n", tag));
#endif
 
    switch (tag)
    {
        case LICENCE_TAG_REQUEST:
            licence_process_request(s);
            break;
 
        case LICENCE_TAG_PLATFORM_CHALLANGE:
            licence_process_platform_challenge(s);
            break;
 
        case LICENCE_TAG_NEW_LICENCE:
        case LICENCE_TAG_UPGRADE_LICENCE:
            /* we can handle new and upgrades of licences the same way. */
            licence_process_new_license(s);
            break;
 
        case LICENCE_TAG_ERROR_ALERT:
            licence_process_error_alert(s);
            break;
 
        default:
            unimpl("licence tag 0x%02x\n", tag);
    }
}